(a) Field of the Disclosure
The present disclosure relates to a microphone and more particularly, to a microphone that improves directional characteristic by applying a plural porous sound delay filter.
(b) Description of the Related Art
Generally, a microphone is a device that converts sound into an electrical signal and is applicable to mobile communication devices that include a terminal (e.g., an earphone or a hearing aid). The microphone requires high audio performance, reliability, and operability. A capacitive microphone based on Micro Electro Mechanical System (MEMS microphone has high audio performance, reliability, and operability, as compared with an electret condenser microphone (ECM microphone). The MEMS microphone is classified into a non-directional (e.g., omnidirectional) microphone and a directional microphone based on the directional characteristics.
The directional microphone has varying sensitivity based on the directions of incident sound waves, and is a unidirectional or a bidirectional type in accordance with the directional characteristics. For example, the directional microphone is used for recording in a narrow room or capturing desired sounds in a room with reverberation. When the microphones are mounted within a vehicle, sound sources are distant and noise is variably generated due to the environmental characteristics of the vehicle.
Accordingly, there is a need for a microphone that filters the noise within the vehicle and it is desired that the directional MEMS microphone captures sounds in desired directions is used. However, there the directional microphone according to the conventional art does not have uniform directional difference based on the frequency bands.
The above information disclosed in this section is merely for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.